Material feeder devices are widely used in many industries to transport particles such as powders, pellets, medicaments, metals, and the like. In compression molding operations, for instance, efficient filling of the molds with materials in the powder form has a significant bearing in determining the unit manufacturing cost (UMC). Feeder boxes are used to carry loose powder to the top of the die where it shakes dropping powder into a die cavity. The die cavity is located underneath a die retaining element or the die retaining ring which secures the die in position. The die cavity is filled by the shaking motion of the feeder box which is connected to a hydraulic actuated cylinder. The feeder box slides on a flat surface called "ware plate" in a reciprocating motion. The time interval between the two extreme locations of the feeder box, when the compacting of the powders in the die cavity is effected. The top surfaces of the ware plate, the die retaining ring and the bottom surface of the feeder box need to be in a continuous plane for smooth operation of the powder filling mechanism. When the die cavity is filled with powder, it is compressed by the action of punches making a "green part". The proper filling of the die cavity depends, among several other factors, on the sliding motion of the bottom of the feeder box on a plate normally known as feeder box ware plate and also on the die clamp (or retaining) ring. If there is a misalignment of the feeder box with respect to the ware plate and also with respect to the die clamp (or retaining) ring or if there is a slight gap between those components, excessive powder loss results. This problem is magnified if the powder particles are very fine (submicron) or are very hard. In such cases, the jamming of the feeder box (in worst case, breakage of the feeder box or ware plate or die clamp ring) can lead to interruption of the manufacturing process and a higher UMC for the part.
Misalignment of the feeder box with respect to the ware plate and/or with respect to die retaining ring can occur due to gouging of one of the surfaces, which is a common occurrence in industrial compression molding machines where the box and the plate and also the clamp ring are usually made of metallic materials, such as steels. Our experience indicates that ceramic materials may have some unexpected advantages in such molding components, although the prior art currently does not support this conclusion. This is because most of the conventional high performance ceramics are extremely brittle. An example of a material having good hardness and strength is monolithic cubic spinel, however, this material is also highly brittle and is unusable for structural applications. Thus skilled artisans are more inclined to experiment with alternative metallic components in materials feeder. Repeated sliding of two surfaces of metal parts, as in this specific case of surfaces of feeder box and the ware plate (or die retaining ring), usually leads to excessive wear and abrasion of those surfaces leading to the loss of materials, contaminating the powder feed, and also creating a gap between the box and the plate and also between the feeder box and the die clamp ring. This gap between the feeder box and the ware plate and also between the feeder box and the die retaining ring leads to the loss of powder, and in some cases jamming of the feeder mechanism. Normally, the machine components will begin to show signs of wear at about 5000 cycles of operation. At about one million cycle, the feeder plate will have to be replaced, if not sooner. Powdered material will start leaking out from under the feeder box and falling on the rest of the movable components of the machine making maintenance a large problem. Also, the motion of the feeder box will become agitated and impede the free flowing motion of powder during die filling.
Therefore, a need persists for improved materials feeder and method of making same so that the equipment will have superior wear and abrasion resistance while being cost effective and easy to manufacture.